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need help on old CRT tv (feddit.fr)

submitted 2 months ago* (last edited 2 months ago) by Salcie@feddit.fr to c/retrocomputing@lemmy.sdf.org

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hi there, wondering if I could get some help here:
I have an old CRT tv black and white, I've plugged it to an HDMI/composite to RF modulator HDM69

It used to work some time ago but can't find out why it doesn't anymore

When I don't plug anything it seems alright (but not sure it really is) but as soon as I plus HDMI or composite my tv doesn't display things right
Notice that it works on my modern tv
Here is a video showing what's happening video

Any ideas ? <3

PS: the horrible noise is my vaccum cleaner

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[–] young_broccoli@lemmy.dbzer0.com 6 points 2 months ago (2 children)

Just guessing here, im no expert.

Could be interference from the vacum. Some old tvs and depending on the electrical circuit they are plugged in dont like when high powered devices are running. A bad electrical circuit can aldo cause this, try plugging it to a regulator.

Badly tunned. Some tvs allow for fine tunning of the chanel they are "listening" to

Bad cable, even if it works on other tvs. Some tvs handle "weak" and/or "dirty" signals better than others.

Bad modulator. Same as cable

Bad tv. In my experience capacitors die and can cause those kinds of failures but I wouldnt recomend poking inside a crt tv if you dont know what you are doing.

BTW, thats a pretty TV. Hope you get it working.

[–] cmnybo@discuss.tchncs.de 3 points 2 months ago (1 children)

Some old tvs and depending on the electrical circuit they are plugged in dont like when high powered devices are running.

It's not really an issue with high powered devices, it's an issue with brushed motors that arc and produce loads of RFI.

[–] young_broccoli@lemmy.dbzer0.com 1 points 2 months ago

TIL. Thanks! ^.^

[–] b_tr3e@feddit.org 2 points 2 months ago (1 children)

Unlikely. The interference from the electric motor just worked because analog TVs used to recieve a (weak) analog signal via antenna. That doesn't apply to the HDMI/RF connector. I suspect the CRT might not be able to deal with the HDMI converter's line frequency. Also., I don't know if the CRT has a separate composite input - if you go in via the antenna input be sure to set the converter to RF, not to composite output if possible. Composite and RF signal are not the same.

[–] young_broccoli@lemmy.dbzer0.com 2 points 2 months ago

Unlikely. The interference from the electric motor just worked because analog TVs used to recieve a (weak) analog signal via antenna.

That may be right, like I said Im not an expert. But when I was a kid we had a tv that misbehaved when the washing machine was working even when watching through composite.

[–] Salcie@feddit.fr 1 points 2 months ago (1 children)

So what is happening is quite simple:

I AM FRENCH

which is considered bad when using old TVs. Why ?

Because we use L and L' bandes when most modulator are using B/G or things like that
So, that won't work properly.

[–] Salcie@feddit.fr 1 points 1 month ago

So I got it working by buying an Terra MT47 modulator !

thanks to @mayasynth@eldritch.cafe and her advices !